In a process of manufacturing a semiconductor substrate, a flat panel display (FPD) represented by a liquid crystal display (LCD), a solar cell, or the like, plasma processing such as etching or film formation using plasma on the substrate is performed. However, such plasma processing has been known to leave a damage layer in a silicon layer. For example, a Fin channel (a silicon standing wall) of a Fin-type channel field effect transistor (FinFET), which is a next-generation three-dimensional (3D) device, may be formed through plasma etching with high anisotropy. It is considered that, during the plasma etching process, ions perpendicularly and anisotropically coming in collide with a substrate so as to spread in multiple directions, thereby leaving plasma damage even on sidewalls of the Fin channel.
In order to recover the damage layer formed on the silicon layer due to the plasma processing, or the like, a method of performing an annealing process at a high temperature ranging from about 900 to 1000 degrees C. for a long time or a method of first forming a sacrificial oxide film by thermally oxidizing silicon in a depth equal to or deeper than that of the damage layer and then removing the sacrificial oxide film by a liquid chemical having selectivity with respect to an underlayer has been employed. However, any of the methods requires heat treatment at a high temperature and this causes an increase in thermal budget. Further, in the latter method, there is a possibility that a fine pattern formed on a substrate collapses during the processing with the liquid chemical (so-called pattern collapse). Thus, in the process of manufacturing a next-generation device including a 3D device, there is a high possibility that it is difficult to apply an annealing process or a sacrificial oxidizing process at high temperatures for a long time for the purpose of recovering plasma damage. Moreover, removing damage from a fine pattern such as a Fin channel requires dimension controllability with high precision.
On the other hand, as a method of forming a fine pattern that can be used in a 3D structure transistor, or the like on a semiconductor substrate, a method of repeatedly performing a process of forming a thin oxide film on a surface of a silicon pattern formed through anisotropy etching and a process of removing the oxide film by exposing it to a mixture gas of HF and NH3 has been proposed in the related art.